It followed the case of Rachel Forber, a 21-year-old woman from Liverpool who had been diagnosed with the disease.

She was bed-ridden and required constant care before taking the drug. Within three months of starting treatment she was able to get out of bed, walk unaided and even swim without support.

However, Rachel died at the end of 2001. It is thought she was taken off the drug after complications affecting her liver.

The trial will also examine the effectiveness of another potential treatment, pentosan polysulphate.

The unlicensed drug was first given to a Belfast teenager with vCJD in 2002. It is directly injected into the brain. The family of Jonathan Simms say it has helped to stablise his condition.

"Despite everything we were told, he remains stable," his father Don told BBC News Online.

The Medical Research Council said the study had been difficult to organise.

"It has been very complex," a spokeswoman told BBC News Online. "We have been breaking new ground."

But she added: "The study has now received ethical approval and we hope it will get underway in the next few weeks."

Potential test

The trial could also assess the effectiveness of a potential test for vCJD.

Dr Chris Pomfrett, a neurophysiologist based at Manchester Royal Infirmary, has developed an electrocardiogram system used in heart monitoring which he believes
can spot early signs of the disease.

The test was developed with £112,000 of government money. Tests on animals suggest it does work. However, Dr Pomfrett has been unable to get access to patients with the disease to see if it works on humans.

"We are looking at whether it can be included in the clinical trials," said a spokesman for the Department of Health.